I’ve tried this with various files (soundslice transcribes from PDF) and the imported musicxml in Dorico is always miserable, music missing, instruments and staves interleaved, etc. Sibelius on the other hand has no problems with them. Here’s an example (Rachmaninoff’s 18th variation):
18th-variation.xml (775.9 KB)
After import into Dorico:
Siblius imports it fine (soundslice transcription is not perfect but it’s imported correctly):
Hi @StephenWeatherford, your example is missing.
(for quick help it would be good if you could upload the XML file produced by Soundslice and a PDF of how it looks in Sibelius)
Was working on it, thanks.
Thank you for the file @StephenWeatherford
TheXML generated by Soundlice is really extremely bad. I tried to open it in Muse Score (which is generally very indulgent with bad XML) and it showed several corruptions with wrong bars lengths…
After opening it anyway, the result is really bad, as it is in Sibelius. Now: try to correct those rhythms in Sibelius…
Generally I would say that MS and S open the file and you have some notes, yes, but the interpretation of the very bad XML is basically unusable.
Dorico doesn’t try to interpret too much:if the XML is bad, then you will see rests (or other strange things as well).
If possible you need to correct the output, checking the original file meticulously in Soundslice for wrong bar lengths or hidden things that produce strange rhythms and so on…before exporting it again, and, with some skills, edit the XML directly (which may be very complicated).
This is only a first impression by me. I am sure someone with more knowledge than me about XML will write something more houseful to you 
.
So is Dorico being stricter about MusicXML structure basically a deliberate design choice?
There is a huge difference between Dorico and the other apps: Dorico does not treat bar as separate containers. It takes the whole music and represents it in the way the user needs it (that’s why it’s easy to change meter without affecting the music heard, for instance. So when a problem occurs in a program where every bar is its own sandbox, the problem is not widely spread to the whole score, but Dorico, not having those sandboxes, is more prone to fail accepting strange peculiarities in XML files. I don’t think it’s deliberate from the dev team to make it stricter, I think it’s a consequence of this (great) paradigm they have built their app on.
I might as well be completely wrong in what I am assuming here, I have to confess 
Turns out MuseScore imported the original PDF much better than soundslice.
